Scientists sifting genetic material from thriving and ailing bee colonies say a virus appears to be a prime suspect — but is unlikely to be the only culprit — in the mass die-offs of honeybees reported last fall and winter.
The honeybee die-offs, in which adult bees typically vanished without returning to hives, were reported by about a fourth of the nation’s commercial beekeepers. The losses captured public attention as rumors swirled about causes ranging from climate change to cell- phone signals to genetically modified crops.
Now, one bee disease, called Israeli acute paralysis virus, seems strongly associated with the beekeeping operations that experienced big losses, a large research group has concluded, although members of the team stressed that they had not proved the virus caused the die-offs.
“I hope no one goes away with the idea that we’ve actually solved the problem,” said Jeffrey S. Pettis, an entomologist with the Department of Agriculture and co-director of a national group working on the puzzle, which has been given the name colony collapse disorder.
The project involved an unusual partnership between entomologists and scientists working at the leading edge of human genetic research. It employed the same technology being used to decode Neanderthal DNA and the personal genome of James Watson, the co- discoverer of DNA.
The research was described in Science Express, the online edition of the journal Science. Details are available at eurekalert.org/ bees.
Even with the caveats, the possible identification of a virus involved in large bee die-offs “is exceptionally important,” said May Berenbaum, who heads the entomology department at the University of Illinois, Urbana-Champaign, and was not involved in the study. “Among other things, figuring out where this one came from will help us prevent future problems.”
Berenbaum, who led a 2006 National Academies study of problems with bees and other pollinators, said that finding ways to swiftly home in on novel diseases is ever more important in a globally linked economy. She noted that the first reports of the latest bee die-offs in the United States came in 2004, the same year the country allowed the first imports of honeybees from another country - - in this case Australia — since 1922.
The new study found evidence of the virus in some Australian bee samples, although that country has not reported die-offs like those seen in the United States.
“Globalization clearly has had impacts on emerging and re- emerging infectious diseases of humans,” said Berenbaum. “Should bees be any different?
Pettis said that even if the virus is involved, it is likely that more than one factor has to align for a hive to collapse, with another possible influence being poor nutrition. Most of the colonies that had big losses over last winter were in areas that experienced drought a few months beforehand, and thus a lack of nectar in flowers, he said.
Another factor, he said, could be the stress that comes from the increasingly industrial-style beekeeping operations in the United States, in which truckloads of hives crisscross the country to pollinate California almonds or Florida orchards each season.
But the virus stands out as a top suspect. While seven viruses and a host of bacteria and parasites were identified in the genetic screening, only the Israeli bee virus, first identified in 2004, was strongly tied to the samples taken from keepers who reported the collapse disorder.
While it was first identified by scientists in Israel, the virus appears to exist in many parts of the world, said W. Ian Lipkin, one of the authors of the new study and director of the Center for Infection and Immunology of Columbia University. When the group screened some samples of Chinese imports of a bee product called royal jelly, they found evidence of the virus as well.
In Israel, it also seems to produce bee symptoms not reported in the United States, including shivering and a pattern of finding dead bees near hives.
Lipkin, whose focus is human disease, became involved because the quest for a cause for the beehive collapses employed new genetic sifting techniques that he said might also prove useful in investigating human disease outbreaks.
One hint of the involvement of an infectious agent, he said, was the recent finding that abandoned hives sterilized with radiation could be repopulated with healthy bees. “That’s how they convinced me to do this research,” he said.
The study initially examined bees from four beekeepers who reported die-offs, as well as healthy bees from Hawaii and Pennsylvania. Genetic material was extracted and analyzed with a machine from 454 Life Sciences, a company immersed in the race to make gene-sequencing a fast, cheap technology.
Statistical analysis showed that a colony with the Israeli virus was 65 times more likely to have had the collapse disorder than one without it.
To try to clarify cause and effect, the researchers said they are preparing a new suite of tests in which isolated bee colonies are infected intentionally with the virus, both with and without possible secondary causes like certain parasites.
Information provided by: Findarticles.com
